Don't insert a final newline in editlines (#320)

src/bin/edit/documents.rs

@@ -114,13 +114,7 @@ impl DocumentManager {
     }
 
     pub fn add_untitled(&mut self) -> apperr::Result<&mut Document> {
-        let buffer = TextBuffer::new_rc(false)?;
-        {
-            let mut tb = buffer.borrow_mut();
-            tb.set_margin_enabled(true);
-            tb.set_line_highlight_enabled(true);
-        }
-
+        let buffer = Self::create_buffer()?;
         let mut doc = Document {
             buffer,
             path: None,
@@ -167,13 +161,10 @@ impl DocumentManager {
             return Ok(doc);
         }
 
-        let buffer = TextBuffer::new_rc(false)?;
+        let buffer = Self::create_buffer()?;
         {
-            let mut tb = buffer.borrow_mut();
-            tb.set_margin_enabled(true);
-            tb.set_line_highlight_enabled(true);
-
             if let Some(file) = &mut file {
+                let mut tb = buffer.borrow_mut();
                 tb.read_file(file, None)?;
 
                 if let Some(goto) = goto
@@ -216,6 +207,17 @@ impl DocumentManager {
         File::create(path).map_err(apperr::Error::from)
     }
 
+    fn create_buffer() -> apperr::Result<RcTextBuffer> {
+        let buffer = TextBuffer::new_rc(false)?;
+        {
+            let mut tb = buffer.borrow_mut();
+            tb.set_insert_final_newline(!cfg!(windows)); // As mandated by POSIX.
+            tb.set_margin_enabled(true);
+            tb.set_line_highlight_enabled(true);
+        }
+        Ok(buffer)
+    }
+
     // Parse a filename in the form of "filename:line:char".
     // Returns the position of the first colon and the line/char coordinates.
     fn parse_filename_goto(path: &Path) -> (&Path, Option<Point>) {

src/bin/edit/state.rs

@@ -6,7 +6,6 @@ use std::ffi::{OsStr, OsString};
 use std::mem;
 use std::path::{Path, PathBuf};
 
-use edit::buffer::TextBuffer;
 use edit::framebuffer::IndexedColor;
 use edit::helpers::*;
 use edit::tui::*;
@@ -164,13 +163,6 @@ pub struct State {
 
 impl State {
     pub fn new() -> apperr::Result<Self> {
-        let buffer = TextBuffer::new_rc(false)?;
-        {
-            let mut tb = buffer.borrow_mut();
-            tb.set_margin_enabled(true);
-            tb.set_line_highlight_enabled(true);
-        }
-
         Ok(Self {
             menubar_color_bg: 0,
             menubar_color_fg: 0,

src/buffer/mod.rs

@@ -250,9 +250,8 @@ impl TextBuffer {
             line_highlight_enabled: false,
             ruler: 0,
             encoding: "UTF-8",
-            // Windows users want CRLF and no final newline.
-            newlines_are_crlf: cfg!(windows),
-            insert_final_newline: !cfg!(windows),
+            newlines_are_crlf: cfg!(windows), // Windows users want CRLF
+            insert_final_newline: false,
             overtype: false,
 
             wants_cursor_visibility: false,
@@ -384,6 +383,12 @@ impl TextBuffer {
         self.newlines_are_crlf = crlf;
     }
 
+    /// If enabled, automatically insert a final newline
+    /// when typing at the end of the file.
+    pub fn set_insert_final_newline(&mut self, enabled: bool) {
+        self.insert_final_newline = enabled;
+    }
+
     /// Whether to insert or overtype text when writing.
     pub fn is_overtype(&self) -> bool {
         self.overtype